/*
** $Id: lua.c,v 1.230.1.1 2017/04/19 17:29:57 roberto Exp $
** Lua stand-alone interpreter
** See Copyright Notice in lua.h
*/

#define lua_c

#include "lprefix.h"

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

#if !defined(LUA_PROMPT)
#define LUA_PROMPT "> "
#define LUA_PROMPT2 ">> "
#endif

#if !defined(LUA_PROGNAME)
#define LUA_PROGNAME "lua"
#endif

#if !defined(LUA_MAXINPUT)
#define LUA_MAXINPUT 512
#endif

#if !defined(LUA_INIT_VAR)
#define LUA_INIT_VAR "LUA_INIT"
#endif

#define LUA_INITVARVERSION LUA_INIT_VAR LUA_VERSUFFIX

/*
** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
** is, whether we're running lua interactively).
*/
#if !defined(lua_stdin_is_tty) /* { */

#if defined(LUA_USE_POSIX) /* { */

#include <unistd.h>
#define lua_stdin_is_tty() isatty(0)

#elif defined(LUA_USE_WINDOWS) /* }{ */

#include <io.h>
#include <windows.h>

#define lua_stdin_is_tty() _isatty(_fileno(stdin))

#else /* }{ */

/* ISO C definition */
#define lua_stdin_is_tty() 1 /* assume stdin is a tty */

#endif /* } */

#endif /* } */

/*
** lua_readline defines how to show a prompt and then read a line from
** the standard input.
** lua_saveline defines how to "save" a read line in a "history".
** lua_freeline defines how to free a line read by lua_readline.
*/
#if !defined(lua_readline) /* { */

#if defined(LUA_USE_READLINE) /* { */

#include <readline/readline.h>
#include <readline/history.h>
#define lua_readline(L, b, p) ((void)L, ((b) = readline(p)) != NULL)
#define lua_saveline(L, line) ((void)L, add_history(line))
#define lua_freeline(L, b) ((void)L, free(b))

#else /* }{ */

#define lua_readline(L, b, p) \
  ((void)L, \
   fputs(p, stdout), \
   fflush(stdout), /* show prompt */ \
   fgets(b, LUA_MAXINPUT, stdin) != NULL) /* get line */
#define lua_saveline(L, line) \
  { \
    (void)L; \
    (void)line; \
  }
#define lua_freeline(L, b) \
  { \
    (void)L; \
    (void)b; \
  }

#endif /* } */

#endif /* } */

static lua_State* globalL = NULL;

static const char* progname = LUA_PROGNAME;

/*
** Hook set by signal function to stop the interpreter.
*/
static void lstop(lua_State* L, lua_Debug* ar) {
  (void)ar; /* unused arg. */
  lua_sethook(L, NULL, 0, 0); /* reset hook */
  luaL_error(L, "interrupted!");
}

/*
** Function to be called at a C signal. Because a C signal cannot
** just change a Lua state (as there is no proper synchronization),
** this function only sets a hook that, when called, will stop the
** interpreter.
*/
static void laction(int i) {
  signal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
  lua_sethook(globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
}

static void print_usage(const char* badoption) {
  lua_printf_err("%s: ", progname);
  if (badoption[1] == 'e' || badoption[1] == 'l')
    lua_printf_err("'%s' needs argument\n", badoption);
  else
    lua_printf_err("unrecognized option '%s'\n", badoption);
  lua_printf_err("usage: %s [options] [script [args]]\n"
                 "Available options are:\n"
                 "  -e stat  execute string 'stat'\n"
                 "  -i       enter interactive mode after executing 'script'\n"
                 "  -l name  require library 'name' into global 'name'\n"
                 "  -v       show version information\n"
                 "  -E       ignore environment variables\n"
                 "  --       stop handling options\n"
                 "  -        stop handling options and execute stdin\n"
                 "  -d       ignore EOF, for debug attaching in MacOSX\n"
                 "  -a list  pass arg list for '-e' option\n",
                 progname);
}

/*
** Prints an error message, adding the program name in front of it
** (if present)
*/
static void l_message(const char* pname, const char* msg) {
  if (pname)
    lua_printf_err("%s: ", pname);
  lua_printf_err("%s\n", msg);
}

/*
** Check whether 'status' is not OK and, if so, prints the error
** message on the top of the stack. It assumes that the error object
** is a string, as it was either generated by Lua or by 'msghandler'.
*/
static int report(lua_State* L, int status) {
  if (status != LUA_OK) {
    const char* msg = lua_tostring(L, -1);
    l_message(progname, msg);
    lua_pop(L, 1); /* remove message */
  }
  return status;
}

/*
** Message handler used to run all chunks
*/
static int msghandler(lua_State* L) {
  const char* msg = lua_tostring(L, 1);
  if (msg == NULL) { /* is error object not a string? */
    if (luaL_callmeta(L, 1, "__tostring") && /* does it have a metamethod */
        lua_type(L, -1) == LUA_TSTRING) /* that produces a string? */
      return 1; /* that is the message */
    else
      msg = lua_pushfstring(L, "(error object is a %s value)", luaL_typename(L, 1));
  }
  luaL_traceback(L, L, msg, 1); /* append a standard traceback */
  return 1; /* return the traceback */
}

/*
** Interface to 'lua_pcall', which sets appropriate message function
** and C-signal handler. Used to run all chunks.
*/
static int docall(lua_State* L, int narg, int nres) {
  int status;
  int base = lua_gettop(L) - narg; /* function index */
  lua_pushcfunction(L, msghandler); /* push message handler */
  lua_insert(L, base); /* put it under function and args */
  globalL = L; /* to be available to 'laction' */
  signal(SIGINT, laction); /* set C-signal handler */
  status = lua_pcall(L, narg, nres, base);
  signal(SIGINT, SIG_DFL); /* reset C-signal handler */
  lua_remove(L, base); /* remove message handler from the stack */
  return status;
}

static void print_version(void) {
  lua_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT));
  lua_writeline();
}

/*
** Create the 'arg' table, which stores all arguments from the
** command line ('argv'). It should be aligned so that, at index 0,
** it has 'argv[script]', which is the script name. The arguments
** to the script (everything after 'script') go to positive indices;
** other arguments (before the script name) go to negative indices.
** If there is no script name, assume interpreter's name as base.
*/
static void createargtable(lua_State* L, char** argv, int argc, int script) {
  int i, narg;
  if (script == argc)
    script = 0; /* no script name? */
  narg = argc - (script + 1); /* number of positive indices */
  lua_createtable(L, narg, script + 1 + 2);
  lua_pushlightuserdata(L, (void*)argv);
  lua_setfield(L, -2, "argv");
  lua_pushinteger(L, argc);
  lua_setfield(L, -2, "argc");
  for (i = 0; i < argc; i++) {
    lua_pushstring(L, argv[i]);
    lua_rawseti(L, -2, i - script);
  }
  lua_setglobal(L, "arg");
}

typedef int (*PushArgs)(lua_State* L, void* ud);
static int dochunk(lua_State* L, int status, PushArgs pushArgs, void* ud) {
  if (status == LUA_OK) {
    int arg = pushArgs != NULL ? pushArgs(L, ud) : 0;
    status = docall(L, arg, 0);
  }
  return report(L, status);
}

static int dofile(lua_State* L, const char* name) {
  return dochunk(L, luaL_loadfile(L, name), NULL, NULL);
}

static int dostring(lua_State* L, const char* s, const char* name) {
  return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name), NULL, NULL);
}

static int pushArgs(lua_State* L, void* ud) {
  char** arge = (char**)ud;
  int arg = 0;
  if (arge != NULL) {
    for (; arge[arg] != NULL; arg++) {
      lua_pushstring(L, arge[arg]);
    }
  }
  return arg;
}
static int doeval(lua_State* L, const char* s, const char* name, char** arge) {
  return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name), pushArgs, (void*)arge);
}

/*
** Calls 'require(name)' and stores the result in a global variable
** with the given name.
*/
static int dolibrary(lua_State* L, const char* name) {
  int status;
  lua_getglobal(L, "require");
  lua_pushstring(L, name);
  status = docall(L, 1, 1); /* call 'require(name)' */
  if (status == LUA_OK)
    lua_setglobal(L, name); /* global[name] = require return */
  return report(L, status);
}

/*
** Returns the string to be used as a prompt by the interpreter.
*/
static const char* get_prompt(lua_State* L, int firstline) {
  const char* p;
  lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
  p = lua_tostring(L, -1);
  if (p == NULL)
    p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
  return p;
}

/* mark in error messages for incomplete statements */
#define EOFMARK "<eof>"
#define marklen (sizeof(EOFMARK) / sizeof(char) - 1)

/*
** Check whether 'status' signals a syntax error and the error
** message at the top of the stack ends with the above mark for
** incomplete statements.
*/
static int incomplete(lua_State* L, int status) {
  if (status == LUA_ERRSYNTAX) {
    size_t lmsg;
    const char* msg = lua_tolstring(L, -1, &lmsg);
    if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0) {
      lua_pop(L, 1);
      return 1;
    }
  }
  return 0; /* else... */
}

static int debugging = 0;

/*
** Prompt the user, read a line, and push it into the Lua stack.
*/
static int pushline(lua_State* L, int firstline) {
  char buffer[LUA_MAXINPUT];
  char* b = buffer;
  size_t l;
  const char* prmt = get_prompt(L, firstline);
  int readstatus = 0;
reread:
  readstatus = lua_readline(L, b, prmt);
  if (readstatus == 0) {
    if (debugging) { // Now for MacOSX only
      printf("\nRead EOF, but debugging...\n");
      goto reread;
    }
    return 0; /* no input (prompt will be popped by caller) */
  }
  lua_pop(L, 1); /* remove prompt */
  l = strlen(b);
  if (l > 0 && b[l - 1] == '\n') /* line ends with newline? */
    b[--l] = '\0'; /* remove it */
  if (firstline && b[0] == '=') /* for compatibility with 5.2, ... */
    lua_pushfstring(L, "return %s", b + 1); /* change '=' to 'return' */
  else
    lua_pushlstring(L, b, l);
  lua_freeline(L, b);
  return 1;
}

/*
** Try to compile line on the stack as 'return <line>;'; on return, stack
** has either compiled chunk or original line (if compilation failed).
*/
static int addreturn(lua_State* L) {
  const char* line = lua_tostring(L, -1); /* original line */
  const char* retline = lua_pushfstring(L, "return %s;", line);
  int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
  if (status == LUA_OK) {
    lua_remove(L, -2); /* remove modified line */
    if (line[0] != '\0') /* non empty? */
      lua_saveline(L, line); /* keep history */
  } else
    lua_pop(L, 2); /* pop result from 'luaL_loadbuffer' and modified line */
  return status;
}

/*
** Read multiple lines until a complete Lua statement
*/
static int multiline(lua_State* L) {
  for (;;) { /* repeat until gets a complete statement */
    size_t len;
    const char* line = lua_tolstring(L, 1, &len); /* get what it has */
    int status = luaL_loadbuffer(L, line, len, "=stdin"); /* try it */
    if (!incomplete(L, status) || !pushline(L, 0)) {
      lua_saveline(L, line); /* keep history */
      return status; /* cannot or should not try to add continuation line */
    }
    lua_pushliteral(L, "\n"); /* add newline... */
    lua_insert(L, -2); /* ...between the two lines */
    lua_concat(L, 3); /* join them */
  }
}

/*
** Read a line and try to load (compile) it first as an expression (by
** adding "return " in front of it) and second as a statement. Return
** the final status of load/call with the resulting function (if any)
** in the top of the stack.
*/
static int loadline(lua_State* L) {
  int status;
  lua_settop(L, 0);
  if (!pushline(L, 1))
    return -1; /* no input */
  if ((status = addreturn(L)) != LUA_OK) /* 'return ...' did not work? */
    status = multiline(L); /* try as command, maybe with continuation lines */
  lua_remove(L, 1); /* remove line from the stack */
  lua_assert(lua_gettop(L) == 1);
  return status;
}

/*
** Prints (calling the Lua 'print' function) any values on the stack
*/
static void l_print(lua_State* L) {
  int n = lua_gettop(L);
  if (n > 0) { /* any result to be printed? */
    luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
    lua_getglobal(L, "print");
    lua_insert(L, 1);
    if (lua_pcall(L, n, 0, 0) != LUA_OK) {
      l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)", lua_tostring(L, -1)));
      lua_settop(L, 0);
    }
  }
}

static void call_registry_funcs(lua_State* L, const char* name, const char* msg) {
  if (lua_getfield(L, LUA_REGISTRYINDEX, name) == LUA_TTABLE) {
    int idx = lua_gettop(L);
    lua_pushcfunction(L, msghandler);
    lua_pushnil(L);
    while (lua_next(L, idx)) {
      if (lua_pcall(L, 0, 0, idx + 1) != LUA_OK) {
        lua_printf_err(msg, lua_tostring(L, -1));
        lua_pop(L, 1);
      }
    }
    lua_pop(L, 1);
  }
  lua_pop(L, 1);
}

/*
** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
** print any results.
*/
static void doREPL(lua_State* L) {
  int status;
  const char* oldprogname = progname;
  progname = NULL; /* no 'progname' on errors in interactive mode */
  while ((status = loadline(L)) != -1) {
    if (status == LUA_OK)
      status = docall(L, 0, LUA_MULTRET);
    if (status == LUA_OK)
      l_print(L);
    else
      report(L, status);
    call_registry_funcs(L, LUA_ATREPL, "Call atrepl failed: %s\n");
  }
  lua_settop(L, 0); /* clear stack */
  lua_writeline();
  progname = oldprogname;
}

/*
** Push on the stack the contents of table 'arg' from 1 to #arg
*/
static int pushargs(lua_State* L) {
  int i, n;
  if (lua_getglobal(L, "arg") != LUA_TTABLE)
    luaL_error(L, "'arg' is not a table");
  n = (int)luaL_len(L, -1);
  luaL_checkstack(L, n + 3, "too many arguments to script");
  for (i = 1; i <= n; i++)
    lua_rawgeti(L, -i, i);
  lua_remove(L, -i); /* remove table from the stack */
  return n;
}

static int handle_script(lua_State* L, char** argv) {
  int status;
  const char* fname = argv[0];
  if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
    fname = NULL; /* stdin */
  status = luaL_loadfile(L, fname);
  if (status == LUA_OK) {
    int n = pushargs(L); /* push arguments to script */
    status = docall(L, n, LUA_MULTRET);
  }
  return report(L, status);
}

/* bits of various argument indicators in 'args' */
#define has_error 1 /* bad option */
#define has_i 2 /* -i */
#define has_v 4 /* -v */
#define has_e 8 /* -e */
#define has_E 16 /* -E */
#define has_d 32 /* -d */
#define has_a 64 /* -a */

/*
** Traverses all arguments from 'argv', returning a mask with those
** needed before running any Lua code (or an error code if it finds
** any invalid argument). 'first' returns the first not-handled argument
** (either the script name or a bad argument in case of error).
*/
static int collectargs(char** argv, int* first) {
  int args = 0;
  int i;
  for (i = 1; argv[i] != NULL; i++) {
    *first = i;
    if (argv[i][0] != '-') /* not an option? */
      return args; /* stop handling options */
    switch (argv[i][1]) { /* else check option */
      case '-': /* '--' */
        if (argv[i][2] != '\0') /* extra characters after '--'? */
          return has_error; /* invalid option */
        *first = i + 1;
        return args;
      case '\0': /* '-' */
        return args; /* script "name" is '-' */
      case 'd':
        args |= has_d;
        break;
      case 'E':
        if (argv[i][2] != '\0') /* extra characters after 1st? */
          return has_error; /* invalid option */
        args |= has_E;
        break;
      case 'i':
        args |= has_i; /* (-i implies -v) */ /* FALLTHROUGH */
      case 'v':
        if (argv[i][2] != '\0') /* extra characters after 1st? */
          return has_error; /* invalid option */
        args |= has_v;
        break;
      case 'e':
        args |= has_e; /* FALLTHROUGH */
      case 'l': /* both options need an argument */
        if (argv[i][2] == '\0') { /* no concatenated argument? */
          i++; /* try next 'argv' */
          if (argv[i] == NULL || argv[i][0] == '-')
            return has_error; /* no next argument or it is another option */
        }
        break;
      case 'a':
        if (argv[i][2] != '\0') {
          return has_error;
        }
        args |= has_a;
        while (argv[i] != NULL) {
          i++;
        }
        *first = i;
        return args;
      default: /* invalid option */
        return has_error;
    }
  }
  *first = i; /* no script name */
  return args;
}

#define EqualByte(str1, str2, idx) ((str1)[idx] == (str2)[idx])
#define Equal3Byte(str1, str2) (EqualByte(str1, str2, 0) && EqualByte(str1, str2, 1) && EqualByte(str1, str2, 2))
// arguments for eval
static char** findarge(char** argv, int hasa) {
  if (hasa) {
    for (int i = 1; argv[i] != NULL; i++) {
      if (Equal3Byte(argv[i], "-a")) {
        return argv + i + 1;
      }
    }
  }
  return NULL;
}

/*
** Processes options 'e' and 'l', which involve running Lua code.
** Returns 0 if some code raises an error.
*/
static int runargs(lua_State* L, char** argv, int n, int hasa) {
  int i;
  char** arge = findarge(argv, hasa);
  for (i = 1; i < n; i++) {
    int option = argv[i][1];
    lua_assert(argv[i][0] == '-'); /* already checked */
    if (option == 'a') {
      return 1;
    }
    if (option == 'e' || option == 'l') {
      int status;
      const char* extra = argv[i] + 2; /* both options need an argument */
      if (*extra == '\0')
        extra = argv[++i];
      lua_assert(extra != NULL);
      status = (option == 'e') ? doeval(L, extra, "=(command line)", arge) : dolibrary(L, extra);
      if (status != LUA_OK)
        return 0;
    }
  }
  return 1;
}

static int handle_luainit(lua_State* L) {
  const char* name = "=" LUA_INITVARVERSION;
  const char* init = getenv(name + 1);
  if (init == NULL) {
    name = "=" LUA_INIT_VAR;
    init = getenv(name + 1); /* try alternative name */
  }
  if (init == NULL)
    return LUA_OK;
  else if (init[0] == '@')
    return dofile(L, init + 1);
  else
    return dostring(L, init, name);
}

/*
** Main body of stand-alone interpreter (to be called in protected mode).
** Reads the options and handles them all.
*/
static int pmain(lua_State* L) {
  int argc = (int)lua_tointeger(L, 1);
  char** argv = (char**)lua_touserdata(L, 2);
  int script;
  int args = collectargs(argv, &script); // args are flags, script indicate the first argument after --
  // check whether the link runtime version number equals the current runtime version number
  luaL_checkversion(L); /* check that interpreter has correct version */
  if (argv[0] && argv[0][0])
    progname = argv[0];
  if (args == has_error) { /* bad arg? */
    print_usage(argv[script]); /* 'script' has index of bad arg. */
    return 0;
  }
  if (args & has_v) /* option '-v'? */
    print_version();
  if (args & has_E) { /* option '-E'? */
    lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */
    lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
  }
  luaL_openlibs(L); /* open standard libraries */
  createargtable(L, argv, argc, script); /* create table 'arg' */
  if (!(args & has_E)) { /* no option '-E'? */
    if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */
      return 0; /* error running LUA_INIT */
  }
  if (!runargs(L, argv, script, args & has_a)) /* execute arguments -e and -l */
    return 0; /* something failed */
  if (script < argc && /* execute main script (if there is one) */
      handle_script(L, argv + script) != LUA_OK)
    return 0;
  if (args & has_d) {
    printf("Support debug attaching...\n");
#if defined(__APPLE__)
    debugging++;
#else
    debugging = 0;
#endif
  }
  if (args & has_i) { /* -i option? */
    doREPL(L); /* do read-eval-print loop */
  } else if (script == argc && !(args & (has_e | has_v))) { /* no arguments? */
    if (lua_stdin_is_tty()) { /* running in interactive mode? */
      print_version();
      doREPL(L); /* do read-eval-print loop */
    }
    // Redirect the output to lua, such as, echo "print('Hello')" | ./lua
    else
      dofile(L, NULL); /* executes stdin as a file */
  }
  call_registry_funcs(L, LUA_ATEXIT, "Call atexit failed: %s\n");
  lua_pushboolean(L, 1); /* signal no errors */
  return 1;
}

int main(int argc, char** argv) {
  int status, result;
  lua_State* L = luaL_newstate(); /* create state */
  if (L == NULL) {
    l_message(argv[0], "cannot create state: not enough memory");
    return EXIT_FAILURE;
  }
  lua_pushcfunction(L, &pmain); /* to call 'pmain' in protected mode */
  lua_pushinteger(L, argc); /* 1st argument */
  lua_pushlightuserdata(L, argv); /* 2nd argument */
  status = lua_pcall(L, 2, 1, 0); /* do the call */
  result = lua_toboolean(L, -1); /* get result */
  report(L, status);
  lua_close(L);
  return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
}
